In vivo imaging of astrocytosis in Alzheimer's disease: an ¹¹C-L-deuteriodeprenyl and PIB PET study.

Abstract

Astrocytosis is an important feature of the neuropathology of Alzheimer's disease (AD), yet there is currently no way of detecting this phenomenon in vivo. In this study we examine the retention of the positron emission tomography (PET) tracer (11)C-L-deuteriodeprenyl (DED), thought to bind activated astrocytes, in 9 patients with moderate to severe AD compared with 11 healthy controls. As a measure of amyloid load, (11)C-labelled Pittsburgh Compound B (PIB) retention was determined. Results show a significantly higher (11)C-L-DED retention in the frontal (35.1% increase, p = 0.001), parietal (35.2%, p = 0.001), temporal (30.9%, p = 0.0001) and medial temporal lobes (22.3%, p = 0.001) in AD compared to healthy controls after blood flow correction. DED retention in the sensorimotor and occipital cortices, and in white matter and subcortical structures, did not differ between groups. There was a moderate but statistically significant (r = 0.492, p = 0.01) correlation between DED and PIB retention values. Our conclusion is that DED may serve as an in vivo marker for astrocytosis in AD, providing a window into intermediate processes between amyloidosis and neuronal loss and a means of monitoring immunotherapy.